Sun Country Airlines and the union representing its flight attendants are seeking federal mediation to help them reach a new contract.

After a proposed agreement was overwhelmingly rejected by flight attendants in May, the Minneapolis-based carrier and the International Brotherhood of Teamsters Local 120 filed jointly on Friday with the National Mediation Board.

Both sides say they believe they will reach agreement faster with federal mediation than by starting over on contract negotiations. The flight attendants are planning an informational picket Tuesday afternoon at Minneapolis-St. Paul International Airport.

"Sun Country is committed to working collaboratively with the International Brotherhood of Teamsters Local 120 to reach an agreement that our 630 flight attendants will be proud to support and that supports the airline's continued growth," Sun Country spokeswoman Wendy Burt said in a statement. "It's important that travelers know that there is no disruption to their flights from [Tuesday's] informational picket. In addition, [Tuesday's] action does not mean there could be a strike in the future."

Burt noted that under federal law, "there are many steps, including a notification to the public, that would have to happen before a strike" and that Sun Country is confident an agreement can be reached.

Rich Fredrick of Teamsters Local 120 said he hopes the union and airline are assigned a mediator and dates quickly. "Based upon our group rejecting the tentative agreement by a 96% no vote, along with the recent rejection of the Allegiant [tentative agreement] by their flight attendants, we are far apart on economics," he said in an email.

The union said in a statement that such a thorough rejection sent a clear message that "this contract is not good enough."

Flight attendants at the Minneapolis-based carrier have been working under a 2014 contract, amended in 2016, with planned negotiations delayed by the pandemic.

Flight attendants want Sun Country to bump up wages and reward staffers for the voluntary furloughs many took during the pandemic.

Entry-level flight attendants now start at $21.53 an hour and can reach $53.56, according to union officials. That scale is stretched across 34 years, however, and the union would like to see it closer to the industry standard 12 to 20 years.

Flight attendants are paid for flight time, and full time is about 85 hours a month. That doesn't include time spent waiting for an aircraft or boarding passengers, though.

Sun Country's pilots approved a new contract in December 2021 that gives them a significant pay increase. The airline's fleet employees and mechanics have also voted to unionize recently.